HTML lang attribute is set

The lang attribute on the <html> element is the primary signal search engines use to serve your page to the correct language audience. Without it, Google may incorrectly categorize or exclude your content from language-segmented search results, reducing organic reach in your target market. Screen readers depend on the lang value to select the right pronunciation engine; an absent or wrong language code causes WCAG 2.2 SC 3.1.1 (Language of Page) to fail, potentially exposing your product to accessibility compliance liability.

Set the lang attribute on the root <html> element. In Next.js App Router this lives in app/layout.tsx:

// app/layout.tsx
export default function RootLayout({ children }: { children: React.ReactNode }) {
  return (
    <html lang="en">
      <body>{children}</body>
    </html>
  )
}

Use a valid BCP-47 code ("en", "en-US", "fr-CA", etc.). For multilingual sites, set the primary language at the root and use per-route lang overrides or hreflang link tags to signal alternate locales.